1. Field of Invention
The present invention relates to a voltage conversion apparatus, and a power-ON reset circuit and a control method thereof; particularly, it relates to such voltage conversion apparatus and power-ON reset circuit and control method thereof which generate a power-ON rest signal according to the statuses of input and output voltages.
2. Description of Related Art
A voltage conversion apparatus converts an input voltage to an output voltage which is provided to a load circuit. When power supplied to the voltage conversion apparatus is reset and restarted (i.e., power-ON reset), a power-ON reset (POR) circuit determines whether the input voltage and the output voltage reach an input voltage predetermined level and an output voltage predetermined level, respectively. When the input voltage reaches the input voltage predetermined level and the output voltage also reaches the output voltage predetermined level, the POR circuit generates a POR signal having a level which indicates that the voltage conversion apparatus is ready for voltage conversion to supply the output voltage properly. When the input voltage or the output voltage does not reach the predetermined level, the POR circuit generates the POR signal having another level which indicates that the voltage conversion apparatus is not ready for voltage conversion to supply the output voltage properly.
One method to achieve voltage conversion is by using a charge pump. However, in existing prior art, the integration of a charge pump with a POR circuit is complicated, resulting in a large-size circuit and a complicated control scheme. Besides, voltage variations may cause the POR circuit to generate an inaccurate POR signal.
In view of above, to overcome the drawbacks in the prior art, the present invention proposes a voltage conversion apparatus and a power-ON reset circuit and a control method thereof, which can generate the POR signal with high accuracy according to the input voltage and the output voltage, and the circuitry is relatively simpler and smaller.